Microcomputer and method for controlling memory access

A microcomputer comprising:

• a CPU (central processing unit) configured to switch a plurality of programs to execute;
• a plurality of protection information storages configured to store memory protection information specifying either an access permission or a prohibited state to a memory space by a program of the plurality of programs executed by the CPU;
• a memory access control unit configured to evaluate whether or not to allow a memory access request from the CPU according to the memory protection information;
• an invalidating unit configured to invalidate all of the plurality of protection information storages in response to a switching of programs executed by the CPU, thereby invalidating memory protection information corresponding to a previously executed program retained in the plurality of protection information storages;
• and
• an updating unit configured to update content of the plurality of protection information storages by memory protection information corresponding to a newly executed program by the CPU after invalidating the memory protection information by the invalidating unit.

A microcomputer comprising:

• a CPU (central processing unit);
• a protection information storage configured to store memory protection information specifying an access permission or a prohibited state to a memory space by a program executed by the CPU;
• a memory access control apparatus configured to determine whether or not to allow a memory access request from the CPU according to the memory protection information;
• and
• a reset apparatus configured to invalidate the memory protection information stored in the protection information storage according to a reset request signal output from the CPU in response to a switching of programs executed by the CPU, the reset request signal being based on a state of execution of the program by the CPU.